NATURAL CONVECTIVE ENHANCEMENT IN A RECTANGULAR ENCLOSURE FILLED WITH NANOFLUID +

Abstract

Heat convective enhancement in a two-dimensional rectangular enclosure utilizingnanofluids is investigated. The basic fluid in the enclosure is an ethylene glycol-basednanofluid containing (Cu, CuO, AL2O3 , or TiO2) nanoparticles. Calculations of heattransfer rates were performed for a range of Rayleigh number (103 ≤Ra≤106), Prandtlnumber is taken as (Pr = 204), and solid volume fraction (0.01 ≤ ı ≤ 0.04). The effects ofRayleigh number and solid volume fraction for different nanofluids on hydrodynamicand thermal characteristics are investigated. Results are presented in the form ofstreamline and isotherm plots as well as the velocity profiles and the variation of localand mean Nusselt number of rectangular enclosure utilizing nanofluids. The resultsindicate that the effects of solid volume fraction grow stronger on the heat transfer ratesfor nanoparticles. In addition, the increases of Rayleigh number leads to decrease thesolid concentration effect. Also, the incremental change in the average Nusselt number isstrongly depending on the nanoparticles chosen. Comparisons with previously publishedwork on the basis of special cases are performed and found to be in excellent agreementwith in maximum error (± 4 ℅).